1. Field of the Invention
The invention relates to the field of digital imaging. Specifically, the present invention is directed towards a method and apparatus for automatic focusing in an image capture system using symmetric FIR filters.
2. Description of Related Art
Use of digital image capture systems such as digital cameras for video and still image capture has become very prevalent in many applications. Video capture may be used for such applications as video conferencing, video editing, and distributed video training. Still image capture with a digital camera may be used for such applications as photo albums, photo editing, and compositing.
Many digital video and still image capture systems use an image sensor constructed of an array of light sensitive elements, each commonly referred to as a xe2x80x9cpixelxe2x80x9d element. Each pixel element is responsible for capturing one of three-color channels: red, green, or blue. Specifically, each pixel element is made sensitive to a certain color channel through the use of a color filter placed over the pixel element such that the light energy reaching the pixel element is due only to the light energy from a particular spectrum. Each pixel element generates a signal that corresponds to the amount of light energy to which it is exposed.
Digital image capture systems are typically expected to operate under a variety of conditions. In addition, features such as auto-focusing and auto-exposure are expected to be integrated features. These are typically hardware intensive processes. In the case of auto-focusing, speed and accuracy is essential for capturing high-quality images. Thus, it would be desirable to implement efficient and hardware friendly auto-focusing processes.